1) Field of the Invention
The present invention relates to a high-speed search apparatus for use with a video disk player.
2) Description of the Related Art
As an example of search method for accessing any position on a moving video disk for a video disk player, where desired information to be retrieved is recorded, by moving an information reading point of a pickup in a radial direction over the video disk at high speed, there is a known method described below. When an address indicated by a frame number or the like, representing a position where desired information has been recorded, is designated as a target address and a high-speed search command is issued, as illustrated in the timing chart of FIG. 1, the information reading point is moved at high speed until it passes the target address (period a). When the information reading point is moved beyond the target address, the direction of the movement is reversed so that the information reading point is moved at high speed in the opposite direction (period b). When it passes the target address again, the direction of the movement is reversed again and the velocity of the movement is lowered (period c). When the information reading point passes the target address, a servo loop of a slider bearing the pickup is closed for reading the address, and a read-out address is compared with the target address (period d). At this time, the information reading point is moved beyond the target address as a matter of course. Therefore a jump command is issued repeatedly to cause the information reading point to jump back in the opposite direction (period e). When the information reading points moves across the target address, the servo loop of the slider is closed (period f), and thereafter a still picture is reproduced by performing a one-track jumping back of the information reading point.
In the conventional high-speed search method as described above, the information reading point is moved to a position adjacent to the target address at high speed and a modification operation to cause the present address to converge the target address is performed while reading the present address from the disk. Thus, the time required to perform the modification operation is relatively long, thereby posing a limitation in reducing the search time. It is also impossible to search a desired image while viewing images reproduced on a screen because the search operation is based on the comparison between the addresses referred to above by using designated target address.
On the other hand, in video reproducing apparatuses such as video tape recorders, video disk players, etc., a technique is employed in which rotary knobs called SHUTTLE ring and a JOG dial are provided concentrically so that the image reproduction speed or image reproducing position is controlled by means of the rotary knobs. With a shuttle reproduction operation using the SHUTTLE ring, a continuous image reproduction is performed at the reproduction speed depending on the angle of rotation of the SHUTTLE ring. Thus, this method is convenient for viewing an outline of information recorded on a video tape or a video disk over a wide range. On the other hand, with a jog reproduction operation using the JOG dial, a reproducing frame in the reproduction of a still picture is changed to an adjacent frame in response to the rotation of the JOG dial, and the image reproducing position is advanced in a fashion of the reproduction of the still picture and in proportion to the amount of rotation of the dial. Thus, this brings about good operational performance and is convenient for the recognition of details of an image.
Where high-speed search using the shuttle or jog reproduction operation, visibility of the image will be reduced since the reproduction is performed by images moving at high speed, causing a difficulty in recognizing desired images, during the execution of the shuttle reproduction operation. On the other hand, in the case of the jog reproduction operation, the high-speed search cannot be achieved over a wide range because the jog reproduction is performed by changing the reproducing frame to the adjacent frame repeatedly as in the reproduction of a still image.